The present invention relates to an expansible bellows, and also to a pulsator device including such a bellows. The invention is particularly useful in the pulse-irrigation method and apparatus described in my prior U.S. Pat. Nos. 4,781,217, 4,949,747, and 5,201,342, and is therefore described below with respect to such an application, although it will be appreciated that the novel expansible bellows, and also the pulsator device including such a bellows, may be used in many other applications.
U.S. Pat. No. 4,781,217 discloses a pulse-irrigation method and apparatus including an expansible chamber having a flow reducer connected to an inlet port of the chamber to produce a continuous slow flow of water into the chamber, and a valve assembly connected to the outlet port of the expansible chamber. The valve assembly is normally closed, automatically opens when the water in the chamber reaches a predetermined pressure, and automatically recloses when the water in the chamber drops to a second predetermined pressure lower than the first predetermined pressure to thereby produce an output in the form of high-pressure water pulses. Such an apparatus is useful for many agricultural applications, e.g., for reducing the water output of sprinklers or of drippers, and also in many non-agricultural applications, e.g., for operating pneumatic or hydraulic power drivers or the like.
The above-cited patent discloses various types of expansible chambers that may be used in the pulsator device, including a resilient tube, a pressurized container, or a vertical tube.
A bellows is another form of expansible chamber which is expansible in the axial direction. It is generally formed in one continuous operation from a thin seamless tube into a deeply folded or corrugated seamless unit. Such constructions, however, are generally quite bulky particularly if they are designed to accommodate high pressures.